Overview: Metoprolol is a beta blocker. It is is used to treat high blood pressure, chest pain, heart failure, and lower the risk of a repeat heart attack. Common side effects include tiredness. Read on to learn about the side effects of metoprolol, including common, severe, and long-term side effects, and how to manage them. Metoprolol, sold under the brand names Lopressor and Toprol-XL among others, is a medication used to treat angina, high blood pressure and a number of conditions involving an abnormally fast heart rate. [5] Metoprolol (Lopressor, Toprol XL) is a beta blocker used to treat high blood pressure, chest pain (angina), and heart failure. Most people take it without serious problems. Metoprolol is used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. View metoprolol tartrate information, including dose, uses, side-effects, pregnancy, breast feeding, contra-indications and monitoring requirements. Metoprolol is a prescription medication used to treat the symptoms of Hypertension, Acute Myocardial Infarction, Congestive Heart Failure, Angina. Learn about side effects, dosages, drug interactions, and more. Get more information about metoprolol, include how it works, what it can be used for, and what to expect when taking the medication. Metoprolol is a beta-blocker medication used to treat high blood pressure, chest pain (angina), and heart failure, and to improve survival after a heart attack. Metoprolol (Lopressor®) is a medication that lowers your blood pressure and heart rate, making it easier for your heart to pump blood to the rest of your body.